Poly(diarylsilmethylene)s,I. Synthesis and characterization

Poly(diarylsilmethylene)s with phenyl or tolyl substituents on Si atoms were synthesized by ring-opening polymerization of corresponding 1,1,3,3-tetraaryl-1,3-disilacyclobutanes, and were characterized by means of DSC, x-ray diffraction and melt viscosity measurements. Three preparative routes including catalytic and noncatalytic polymerization methods were examined to see differences in properties of the resulting polymers. The polymers thus obtained were crystalline and soluble in limited solvents such as diphenyl sulfone at tem-peratures above 250°C. Poly(diphenylsilmethylene) exhibited a melting temperature of about 350°C, whereas those of polymers with tolyl groups were observed in a temperature range between 310 and 330°C. The melt viscosity of the poly(diarylsilmethylene)s was measured to obtain insight into the molecular weights of the polymers, and the results indicated that the molecular weights are modifiable by varying the monomer-to-catalyst ratio when solution polymerization is employed. The DSC and x-ray studies were also carried out with focusing on the melting and crystallization behavior of these polymers. © 1995 John Wiley & Sons, Inc.     

Poly(pentamethylcyclopentasiloxane). I. Synthesis and characterization

We have discovered that pentamethylcyclopentasiloxane (D₅H) can be readily polymerized into poly(pentmethylcyclopentasiloxane) (PD₅) with a Pt (Karstedt) catalyst in the presence of water in bulk or in solution at 100 °C and that the product is a solid with extraordinary properties. The polymerization starts with the oxidation of the SiH groups by water into an intermediate containing SiOH groups (SiH + H₂O → SiOH + H₂), which is followed immediately by the condensation (2SiO → Si? O? Si) of D₅H rings into complex aggregates of cyclosiloxane moieties. According to Raman spectroscopy, an average of three of the five SiH functionalities are converted, and the final product contains only a negligible number of SiOH groups. The melting and glass‐transition temperatures of the monomer are exceptionally low: T_m,D5H = ?137.6 ± 1 and T_g,D5H = ?152 ± 2 °C. The polymer exhibits an unprecedented combination of properties: it is a stiff and brittle solid, is insoluble in common solvents, does not exhibit a melting endotherm but has an extremely low glass transition (T_g,PD5 = ?151 ± 0.5 °C), and is thermally stable up to at least 700 °C. Brillouin scattering indicates very slow variation of the relaxation time with temperature, a property characteristic of strong glass‐forming systems such as silica glass. This characteristic may account for the unique combination of properties of the new polymer: an extremely low glass‐transition temperature combined with solidlike properties even at ambient temperature (more than twice its glass‐transition temperature). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1285–1292, 2002     

Poly(bismethylene hydroquinone) (PBHQ). I. Synthesis and characterization

Poly(bismethylene hydroquinone) (PBHQ) has been synthesized. Fourier transform infrared, ¹³C solid-state CP/MAS NMR and elemental analysis provide strong evidence of two methylene bridges per hydroquinone molecule. The polymer was (1) air oxidized using ammonia and (2) chemically oxidized using bromine/KOH. The initial structure and oxidation process was studied by comparison of the unoxidized and oxidized polymers using Fourier transform infrared, elemental analysis, and ¹³C solid-state CP/MAS NMR.     

Poly(ethylene terephthalate) copolymers containing nitroterephthalic units. I. Synthesis and characterization

The synthesis, microstructure, and thermal behavior of a series of poly(ethylene terephthalate) (PET) copolymers containing nitroterephthalic units are described. These novel copolyesters were synthesized by transesterification followed by melt copolycondensation of dimethyl terephthalate and dimethyl nitroterephthalate mixtures with ethylene glycol. The molar ratio of the two comonomers in the feed varied from 95/5 to 25/75. Furthermore, PET and poly(ethylene nitroterephthalate) homopolymers were synthesized with the same method and comparatively studied. Copolyester compositions were practically the same as in the feed, and weight‐average molecular weights ranged from 10,000 to 60,000. The two monomeric units were randomly distributed along the polymer chain, and the experimentally determined average sequence lengths were in accordance with ideal copolycondensation statistics. Melting temperatures and enthalpies of the copolyesters decreased with increasing content in nitroterephthalic units, and they all showed a single glass‐transition temperature superior to that of PET. They appeared to be stable up to 300 °C, and thermal degradation occurred in two well‐differentiated steps. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3761–3770, 2000     

Poly(methylene sebacate): Synthesis and characterization

The synthesis of poly(methylene sebacate) was carried out via the reaction of cesium sebacate with bromochloromethane in N-methylpyrrolidone over a range of temperatures (55–130°C). A number of polymers having limiting viscosity numbers in the range of 0.29–0.94 dL g^?1 (CHCl₃; 25°C) were characterized by elemental analyses, ¹H- and ¹³C-NMR, DSC, and GPC techniques. The polymerization was found to be very rapid at 100°C, being complete in ca. 15 min. and was relatively insensitive to the stoichiometric ratio of the monomers. As high molecular weight polymers were produced without the quantitative conversion of the reactants, the polymerization is considered to be occurring by an interfacial mechanism.     

Poly(ethylene terephthalate) copolymers containing 5‐nitroisophthalic units. I. Synthesis and characterization

Poly(ethylene terephthalate‐co‐5‐nitroisophthalate) copolymers, abbreviated as PETNI, were synthesized via a two‐step melt copolycondensation of bis(2‐hydroxyethyl) terephthalate and bis(2‐hydroxyethyl) 5‐nitroisophthalate mixtures with molar ratios of these two comonomers varying from 95/5 to 50/50. Polymerization reactions were carried out at temperatures between 200 and 270 °C in the presence of tetrabutyl titanate as a catalyst. The copolyesters were characterized by solution viscosity, GPC, FTIR, and NMR spectroscopy. They were found to be random copolymers and to have a comonomer composition in accordance with that used in the corresponding feed. The copolyesters became less crystalline and showed a steady decay in the melting temperature as the content in 5‐nitroisophthalic units increased. They all showed glass‐transition temperatures superior to that of PET with the maximum value at 85 °C being observed for the 50/50 composition. PETNI copolyesters appeared stable up to 300 °C and thermal degradation was found to occur in two well‐differentiated steps. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1934–1942, 2000     

Poly(methyl methacrylate-g-urethane). I. Synthesis

Poly(methyl methacrylate-g-urethane) was prepared by coupling between poly(methyl methacrylate-co-2-hydroxyethyl methacrylate) and polyurethane. The polyurethane was obtained by bulk polycondensation of tolylene diisocyanate and polypropylene glycol. The two polymeric species were synthesized and characterized separately, and the composition of the grafted products varied only by the spacing of the grafted segments. Grafted copolymers with 5, 10, 20, 25, 40, 50, 70, and 90% of incorporated polyurethane have been prepared.     

Poly(N-acylethylenimine) copolymers containing pendant pentamethyldisiloxanyl groups. I. Synthesis

10-(Pentamethyl disiloxanyl) decyl oxazoline ( Si ) was synthesized. It was copolymerized with either undecyl ( U ) or nonyl ( N ) oxazolines using methyl 4-nitrobenzenesulfonate as initiator. Two series of random poly(N-acylethylenimine) copolymers, U/Si and N/Si , were synthesized over the whole composition range of Si monomer with a total degree of polymerization of about 100. Narrow molecular weight distributions were obtained. At a monomer to initator ratio of about 1060, the final degree of polymerization was 374 with a polydispersity index of 1.93. This shows the effect of chain transfer in this system.     

New Poly(4-Chloro)Maleimides. I. Synthesis and Characterization of Poly[Ether-Ester-(4-Chloro)Maleimides]

Abstract

New poly[N-(ester)-3-(ether)-4-(chloro)]maleimides were synthesized by the reaction of N-(4-chlorocarbonylphenyl)-3,4-dichloromaleimide (3) with various bisphenols such as hydroquinone (8a), 2,2-bis-(4-hydroxyphenyl)propane (8b), 4,4′ -(hexafluoroisopropylidene)diphenol (8c), and 2,5-bis(4-hydroxybenzylidene)cyclopentanone (8d). The structures of the resulted polymers were confirmed by IR and elemental analyses. A series of model compounds (4–7) was synthesized to facilitate confirmation of the structure of the polymers. The polymer containing hydroquinone units (9a) exhibited LC behavior in the melt, as observed by PLM measurements.     

Poly(aryl ethers) by nucleophilic aromatic substitution. I. Synthesis and properties

A series of new aromatic polyethers have been prepared by solution condensation polymerization. The synthesis involves the condensation of a dialkali metal salt of a dihydric phenol with an “activated” or negatively substituted aromatic dihalide in an anhydrous dipolar aprotic solvent at elevated temperatures. The reaction is rapid, free of side reactions, and yields polymers of excellent color. Bakelite polysulfone can be prepared in this manner by reaction of the disodium salt of bisphenol A with 4,4′-dichlorodiphenyl sulfone in dimethyl sulfoxide (DMSO). Only dipolar aprotic solvents are useful for conducting the polymerization. Of these, DMSO and Sulfolane (tetrahydrothiophene 1,1-dioxide) are the most effective. Water or other competing nucleophiles must be absent if high molecular weight is to be obtained. Besides providing the necessary solubility, this highly polar solvent is believed to be essential in providing the rapid polymerization rates observed. The rates are further found to depend on the basicity of the bisphenol salt and upon the electron-withdrawing power of the activating group in the dihalide. As is usual for this type of reaction, the difluorides are found to be more reactive than the corresponding dichlorides. Most of the polyethers are amorphous, rigid, tough thermoplastics with high second-order transitions (T_g). Thermal stability and electrical properties are noteworthy. These and other properties are described for polysulfone, and glass transitions are given for a selected list of the other polyethers.     

Synthesis and characterization of Poly(N-isopropylacrylamide)/Poly(acrylic acid) semi-IPN nanocomposite microgels

A novel pH- and temperature-sensitive nanocomposite microgel based on linear Poly(acrylic acid) (PAAc) and Poly(N-isopropylacrylamide) (PNIPA) crosslinked by inorganic clay was synthesized by a two-step method. First, PNIPA microgel was prepared via surfactant-free emulsion polymerization by using inorganic clay as a crosslinker, and then AAc monomer was polymerized within the PNIPA microgel. The structure and morphology of the microgel were confirmed by FTIR, WXRD and TEM. The results indicated that the exfoliated clay platelets were dispersed homogeneously in the PNIPA microgels and acted as a multifunctional crosslinker, while the linear PAAc polymer chains incorporated in the PNIPA microgel network to form a semi-interpenetrating polymer network (semi-IPN) structure. The hydrodynamic diameters of the semi-IPN microgels ranged from 360 to 400 nm, which was much smaller than that of the conventional microgel prepared by using N,N′-methylenebis(acrylamide) (MBA) as a chemical crosslinker, the later was about 740 nm. The semi-IPN microgels exhibited good pH- and temperature-sensitivity, which could respond independently to both pH and temperature changes.     

Compatibility of Poly(vinyl chloride) with Polyalkyleneoxides. I. Poly(methylene oxide) and Poly(ethylene oxide)

The compatibility of poly(vinyl chloride) (PVC) with linear polyethers is examined over the entire composition range. This study examines blends with poly(methylene oxide) (PMO) and poly(ethylene oxide) (PEO) of medium (MMW) and high (HMW) molecular weight. The techniques used are dynamic mechanical analysis, DSC, and optical microscopy (phase contrast and polarizing). The results indicate that all polyethers show limited miscibility in the melt at high PVC contents. Proper analysis of the T_m data using the Kwei-Frisch and Hoffman-Weeks procedures allows the determination of the thermodynamic interaction parameter, which is found to be close to zero for all pairs of blends.     

Organosilane polymers. I. Poly(dimethylsilylene)

Poly(dimethylsilylene) higher polymers prepared by alkali metal coupling of purified dimethyldichlorosilane were found to be high melting, largely crystalline polymers, soluble in solvents at temperatures above 200°C.     

(Halomethyl)arsenic compounds : I. Synthesis and characterization of (chloromethyl)arsine

(Chloromethyl)arsine, ClCH₂Ash₂, can be prepared by the reduction of chloromethylarsonic acid. Bromomethyl and iodomethyl analogs could not be prepared. NMR, IR, and mass spectra data are included.     

Synthesis and characterization of certain new poly(bisimide)s. I

Maleic and citraconic anhydrides were reacted with several diamines to obtain a novel class of high temperature resistant bisimides.^1–3 The bisimides were characterized by melting points, elemental analysis, UV–Vis, ¹H- and ¹³C-NMR, and mass spectral analysis. The bisimide monomers were then polymerized by the addition process. A poly(amidemaleimide) was also synthesized by reacting maleic anhydride with p-aminobenzhydrazide. The thermal stability of these highly crosslinked poly(bisimide)s were examined by TGA and DTA. A neat bisimide monomer obtained from 2,2′-bis[4(p-aminophenoxy)phenyl] propane with maleic anhydride namely, 2,2′-bis[4-(p-maleimidophenoxy)phenyl]propane was reacted with 2,2′-bis[4(p-aminophenoxy)phenyl]propane by the Michael reaction.⁴ A fiber glass cloth reinforced laminate was prepared from bismaleimide and amine mixture and the mechanical properties of the test laminate evaluated.     

Poly(amideimide)s containing pendant pentadecyl chains: Synthesis and characterization

A new aromatic diacylhydrazide monomer viz., 4-[4′-(hydrazinocarbonyl)phenoxy]-2- pentadecylbenzohydrazide was synthesized starting from cardanol, which in turn is obtainable from cashew nut shell liquid - a renewable resource material. A series of new poly(amideimide)s containing flexibilizing ether linkages and pendant pentadecyl chains was synthesized from 4-[4′-(hydrazinocarbonyl)phenoxy]-2-pentadecylbenzohydrazide and commercially available aromatic dianhydrides, viz., benzene-1,2,4,5-tetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride, benzophenone-3,3′,4,4′-tetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride and 4,4′-(hexafluoro isopropylidene)diphthalic anhydride by a two-step solution polycondensation in N,N-dimethylacetamide via the poly(hydrazide acid) intermediate. Inherent viscosities of poly(amideimide)s were in the range 0.60-0.64 dL/g in N,N-dimethylacetamide at 30 ± 0.1 °C. Poly(amideimide)s could be solution cast into tough, transparent and flexible films from their N,N-dimethylacetamide solutions. The solubility of poly(amideimide)s was significantly improved by incorporation of pendant pentadecyl chains and were found to be soluble in N,N-dimethylacetamide, 1-methyl-2-pyrrolidinone, pyridine and m-cresol at room temperature or upon heating. Wide angle X-ray diffraction patterns of poly(amideimide)s revealed a broad halo at around 2θ = ∼19° suggesting that polymers were amorphous in nature. In the small-angle region, diffuse to sharp reflections of a typically layered structure resulting from the packing of pentadecyl side chains were observed. The temperature at 10% weight loss (T₁₀), determined by TGA in nitrogen atmosphere, of poly(amideimide)s was in the range of 388-410 °C indicating their good thermal stability. Glass transition temperatures of poly(amideimide)s were in the range 162-198 °C. It was observed that the plasticization effect of attached pentadecyl side chains induced the depression of T_g.     

Reaction of diarylzinc compounds with copper(I) salts. Synthesis and characterization of arylcopper(I) compounds

The reaction of diarylzinc compounds with copper(I) salts is an excellent way of preparing stable arylcopper compounds in quantitative yields. These compounds have been characterized by IR, and by ¹H and ¹³C NMR spectroscopy. Cryoscopic molecular weight determinations show phenylcopper to be polymeric and 2-methylphenylcopper and 2,6-dimethylphenylcopper to be tetrameric in benzene. The compounds are believed to contain aryl groups bridging two copper atoms. Evidence is presented for rotation of these aryl groups around the C(1)—C(4) axis.     

Synthesis and solution properties of comblike poly(mono-n-alkyl itaconates). I. Poly(monodecyl itaconate)

The monoester of itaconic acid with n-decyl alcohol was prepared and polymerized. The polymer was fractionated and characterized by viscometry, size-exclusion chromatography (SEC) and light scattering. Some of the common semiempirical relations for flexible and rigid polymers were used in order to obtain the unperturbed dimensions and the conformational parameters. Thermodynamic and dimensional parameters were determined and calculated. The results are compared with those reported previously for similar compounds.     

Novel polyisobutylene/poly(dimethylsiloxane) bicomponent networks. I. Synthesis and characterization

The synthesis of novel polyisobutylene (PIB)/poly(dimethylsiloxane) (PDMS) bicomponent networks is described. The synthesis strategy (see Figure 1) was to prepare well-defined and -characterized allyl-tritelechelic polyisobutylenes [ϕ(PIB—C—C=C)₃] and SiH-ditelechelic poly(dimethylsiloxanes) (HSi–PDMS–SiH) and then crosslink these moieties by hydrosilation. The ϕ(PIB—C—C=C)₃ was prepared by living isobutylene polymerization followed by end-quenching with allyltrimethylsilane, whereas the HSi–PDMS–SiH was obtained by equilibrium polymerization of octamethylcyclotetrasiloxane and tetramethyldisiloxane. The detailed structures of the starting polymers were characterized by GPC and ¹H-NMR spectroscopy. A series of PIB/PDMS bicomponent networks of varying compositions and average molecular weights between crosslinks (M _c) of ∼ 20,000 g/mol were assembled. Optimum crosslinking conditions were defined in terms of H₂PtCl₆ catalyst concentration, nature of solvent, time, temperature, and stoichiometry of ∼ CH₂CH=CH₂/∼SiH groups, allowing for the convenient synthesis of well-defined model bicomponent networks. Swelling studies and elemental analysis confirm the correctness of the synthetic strategy. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1891–1899, 1998